Explosive bag



Jan. 24, 1961 R. J. WHITE 2,969,101

EXPLOSIVE BAG Filed Sept 18, 1958 3 Sheets-Sheet l INVENTOR Pam's J 144/02- Jan. 24, 1961 R. J. WHITE 2,969,101 I EXPLOSIVE BAG Filed Sept. 18, 1958 a Sheets-Sheet 2 INVENTOR P1011224 J 1444/72- R. J. WHITE EXPLOSIVE BAG Jan. 24, 1961 3 Sheets-Sheet 3 Filed Sept. 18, 1958 INVENT OR 44m? \Z'M w/z- BY @W M TORNEY5 United States Patent EXPLOSIVE BAG Russell J. White, Lansdowne, Pa., assignor to Chase Bag Company, New York, N.Y., a corporation of Delaware Filed Sept. 18, 1958, Ser. No. 761,847

4 Claims. (Cl. 150---.5)

This invention relates to explosive bags of tubular form designed to contain a charge of loose explosive material.

An object of the present invention is the provision of an explosive bag which will be watertight and resistant to abrasion.

A further object is the provision of an explosive bag which, when filled, will present a rounded or pointed bottom end well adapted to find its way down a rough and irregular hole.

A further object is the construction of such bags in a way that will allow the use of cheap materials and will require little labor in manufacture.

Further objects will become obvious from the following specifications, in which:

Fig. 1 is a side view of a finished bag in use;

Fig. 2 is a perspective view of the bag end filled;

Fig. 3 is a cross-section on line 3--3 of Fig. 1;

Fig. 4 is a perspective view of an inner shell;

Fig. 5 is a perspective view of a fabric strip;

Fig. 6 is a perspective view of the bag assembly;

Fig. 7 is another perspective view of the bag assembly;

Fig. 8 is a perspective view of the bag end empty;

Fig. 9 is a cross-section on line 9--9 of Fig. 7 but with the gusset spread apart slightly;

Figs. 10, 11, and 12 are perspective end views of alternative types of end construction with the bag empty.

Industry today uses large quantities of loose explosive such as ammonium nitrate. This explosive is packed into bags and lowered into drilled holes. The ideal bag for this purpose must be cheap, easy to load, waterproof, able to stand considerable rough treatment without rupture, reasonably impermeable to oil, and so constructed that it may be lowered into a relatively irregular hole without snagging or ripping on the sides of the hole. The present invention realizes all these requirements.

An understanding of the present invention may best be gained by a consideration of the steps taken in the manufacture of the bag. As a first step an outer shell is formed. A fabric strip 10 is cut to a width equal to the perimeter (taken in cross-section) of the desired outer shell plus an allowance for a seam. Burlap may be used because of strength and its low cost. The fabric strip is fed into a tube forming machine where a strip of paper 11 is positioned on its surface and the edges 13, 13 are overlapped, pressed onto the paper strip, and glued together in a longitudinal seam 17; the paper strip serving to prevent any excess adhesive from gluing the longitudinal seam thus formed to the opposite wall of the fabric tube. A Waterproof adhesive is used for the longitudinal seam. It will be understood that the longitudinal seam may be sewn or fastened by other means known to the art, such as staples, but that gluing is the preferred method, since it results in a smooth seam which is not likely to snag on the hole wall 40 and since there is no danger of abrasion opening the seam, as may be the case if it is sewn. Similarly, the outer shell may be formed of fabric woven as a seamless tube. In lieu of fabric, a wet strength, stretchable kraft paper having a "ice basis weight of or pounds per 500 sheet of 24 inch by 36 inch size may be used.

An inner shell 14 is formed of a flexible waterproof material. Extruded polyethylene film having a thickness of two to five mils has proven satisfactory in practice because of cost considerations and because it is oil resistant but other elastorners will serve in some cases.

The perimeter of the inner shell is preferably slightly greater than that of the outer shell, since this allows the pressure of the bag contents to press the inner shell against the outer without stretching the relatively weak inner shell. Thus the outer shell will provide support for the inner. It will be understood, However, that the inner shell might be made with a smaller perimeter than the outer if an elastic material such as polyethylene is used which can stretch without rupturing until it rests against the outer shell.

The inner shell 14 is sealed at one end with a watertight seal 15. Where polyethylene is used, heat and pressure alone will sufiice. The seal should either be located a short distance from the bottom end 16 of the inner shell or should be wide enough so that when a bottom fold is formed and sewn shut as described below the needle will not penetrate the inner shell above the seal. The inner shell is preferably cut longer than the outer shell. The inner and outer shells are assembled as shown in Fig. 6 with the inner shell extending beyond the outer in extension 30. Fig. 6 shows the seam 17 opened at the bottom to expose the construction. The assembled shells are folded over a longitudinal fold line A-A as shown in Fig. 7, dividing the shells into two side panels 18 of equal width meeting in a common longitudinal fold 23 (Fig. 9). Folding about line AA forms the inwardly extending fold or gusset 31, the innermost points 32 of which reach to the fold line AA in which the side panels meet.

Next the assembled shells are folded over at the bot tom end 19 about a transverse end fold line 13-13 as shown in Fig. 8. This end fold is sewn shut by stitches 20. These stitches pierce the inner shell, and in order to maintain its watertight integrity they should not pierce it above the seal 15. For this reason, as explained above, the top of the seal should be some distance above the bottom edge 16 of the inner shell. It will be understood that other means of holding the end fold shut may be adopted which will work as well as stitching. Staples, a crimped-on metal strip, or gluing under pressure will work, but stitching has proved cheapest. It will also be understood that the end fold may be formed before the longitudinal fold and the longitudinal fold superimposed on the end fold as in Fig. 10, instead of the end fold being superimposed on the longitudinal told as shown in Fig. 8. Further, it is possible to make a bag which will prove satisfactory without the use of an end fold at all. Since the strain of containing the internal pressure of the contents falls on the longitudinal scam in the outer shell and the seal used in the inner shell, there is little internal pressure on the bottom fold. The real tension on the end seam when the bag is loaded comes at the point 21 (Figs. 3 and 8). The bag may be constructed without an end fold simply by sewing a strong end seam across the longitudinally folded assembly below the seal as shown in Fig. 11. Alternatively, the bottom may be closed by sewing a fiat tape 36 across it as shown in Fig. 12. The present construction uses the end fold because it prevents the burlap outer shell from unraveling up to the seam, because it forms a slight buffer 22 (Fig. 2) at the tip of the bag which prevents some abrasion when the filled bags are handled and dragged around, and because it is easy to make.

The bag is filled with explosives through the open end, the extension 30 aids in this process. The end is tied with wire 34 (see Fig. 1). An unusual and desirable feature of the present construction is that under the pres sure of the contents the lower end will inflate into a rounded point, as shown in Fig. 2, the gusset opening out to give a circular cross-section in the body of the bag. This is a great advantage since the holes into which the bags are lowered are often rough and prone to snag them. If a bottom closure such as that found in the ordinary toothpaste tube (a simple seam across the tube) were used, there would be increased danger of snagging and of ripping the bag open through abrasion of the protruding corners.

The foregoing will serve to illustrate the principles of the invention which, of course, are susceptible of embodiment in numerous forms to meet the exigencies of particular cases.

The following is claimed:

1. An explosive bag comprised of an outer fabric shell of flattened tubular form having a desired cross-sectional perimeter and a longitudinal seam fastened with waterproof adhesive; an inner flattened tubular shell comprised of flexible waterproof material having a cross-sectional perimeter slightly exceeding the cross-sectional perimeter of the outer shell and a length exceeding that of said outer shell, said inner shell having a transverse liquidtight seal adjacent its bottom end and said inner shell projecting out of the outer shell at the top of said outer shell, said shells being formedv into two similar side panels meeting in a common longitudinal fold, into a gusset enclosed between the side panels and extending inward to the common longitudinal fold, and into a transverse end fold superimposed on and transverse to the longitudinal fold; and a sewn seam through the end fold penetrating the inner shell between its bottom end and said transverse seal.

2. An explosive bag as claimed in claim 1 wherein the flexible material is extruded polyethylene film and the transverse seal is a heat seal.

3. An explosive bag comprised of an outer fabric shell of flattened tubular form having a desired cross-sectional perimeter and a longitudinal seam fastened with waterproof adhesive; an inner flattened tubular shell comprised of flexible waterproof material having a crosssectional perimeter slightly exceeding the cross-sectional perimeter of the outer shell and a length exceeding that of said outer shell, said inner shell having a transverse liquid-tight seal adjacent its bottom end and said inner shell projecting out of the outer shell at the top of said outer shell, said shells being formed into two similar side panels meeting in a common longitudinal fold, into a gusset enclosed between the side panels and extending inward to the common longitudinal fold, and into a transverse end fold transverse to the longitudinal fold, said longitudinal fold being superimposed on the transverse end fold; and a sewn seam through the end fold penetrating the inner shell between its bottom end and said transverse seal.

4. An explosive bag as claimed in claim 3 wherein the flexible material is extruded polyethylene film and the transverse seal is a heat seal.

References Cited in the file of this patent UNITED STATES PATENTS 445,329 Kerr Jan. 27, 1891 757,610 Flowers Apr. 19, 1904 1,524,190 McNeil Jan. 27, 1925 2,103,092 Robinson Dec. 21, 1937 2,127,012 Spangler Aug. 16, 1938 2,435,743 Geimer Feb. 10, 1948 2,631,630 Brady Mar. 17, 1953 2,788,039 Schjeldahl Apr. 9, 1957 2,878,849 Lingenfelter et al Mar. 24, 1959 2,915,098 McKay Dec. 1, 1959 FOREIGN PATENTS 531,448 Germany Aug. 10, 1931 

